What is the meaning of each stanza in Auden's poem "Spain"? What do the terms "counting frame," "column of stone," and "mover" mean in the poem?

This political poem by Auden is rife with allusions, many of which can be confusing. In the first stanza, he is describing "the past," specifically the growth of trade and globalization. He pairs the "counting-frame," or abacus used by tradesmen, with "the cromlech," the Welsh word for grave, to show how diverse were the cultures now coming into contact.
In the third stanza, he is referring to the development of the world beyond "fairies and giants," or belief in the old ways, and into a time of cathedral building and intense Christianity—"the carving of angels and alarming gargoyles" on vast cathedrals and churches being built at this time.
The "columns of stone" in the following stanza, then, refer back to these cathedrals. Auden is here talking about the many "trials of heretics" which occurred in the medieval period.
When Auden talks about the "belief in the absolute value of Greek" as something belonging to "yesterday," this is an allusion to school days and a time when theoretical and abstract things seemed of great importance, as opposed to "the struggle." However, it could also allude to the Greek volunteers who came to help in the Spanish Civil War because of shared political leanings, most of whom died—"the death of a hero."
Stanza seven is simply a rather romantic imagining of the "poet" in the abstract attempting to capture the realities of the present day, specifically Spain. The poet is imagined appealing, using archaic language ("O"), to greater powers to send him "the luck of the sailor," an idiom for good luck, in order to survive and prosper in these dark days.
In stanza, eight, the poet is contrasted to the "investigator," who uses instruments to map what is going on in the "provinces" he sees as "inhuman." The term "bacillus" means bacteria, so essentially this investigator is imagined as a scientist viewing the people of the country as a spreading disease. By contrast, the poet inquires about "the lives of my friends." These friends themselves are the "poor" who, in the following stanza, see each day as a loss and look forward to "time the refreshing river" as being the only thing which can possibly replenish the land and help organize things again.
When talking about the "city state of the sponge," the speaker is addressing the "life" force, or God. So, he is here asking: did you not found these underwater cities, creating everything that lives there, including living sponge? Did you not also create the tiger and the shark?
When "the life" answers, it says it is not "the mover," a term often applied to God as indicative of his powers of creation. In this instance, the life suggests that it is helpless and actually it is the people who must "move" the situation on.
In stanza 12 he refers to Africa as a "tableland scored by rivers." This is a reference to Africa's geographical features but also to how it was divided up on a table by Europeans, who drew countries onto it on a map and then divided it between them. He then goes on to describe mental "fever" as having shape and being alive: our fears can cause things to happen or not happen in reality. Fears which once made us susceptible to advertising (the "medicine ad," stanza 13) were originally because we did not want to die, but these fears can overtake us and lead us to "ruin."
In stanzas 19 and 20, Auden refers to the difficulties of "today" for those fighting the war on the ground, so different from the propaganda "pamphlet" and rally that might have drawn people to fight.